unit 2 – lecture 4 periodic table describes trends in physical and chemical properties number of...
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Unit 2 – Lecture 4
Periodic TableDescribes trends in physical and chemical
propertiesnumber of electrons, protons, neutronschargereactivitytype of element
PropertiesChemical Properties are based on the number
of valence e-sElements in same group/family elements
have same # of valence e-s group 1 = 1, group 2 = 2group 13-18, drop the “1” in front of the
group #ex: 13 = 3, 14 = 4
Helium has 2Groups 3-12 use a different set of electrons,
so it doesn’t follow the typical pattern
ChargeRecall: “Octet Rule”atoms will gain, lose, or share e-s to
become chemically stable [8 e-s in valence shell]
PT indicates charge by groups as wellagain, groups 3-12 are left out of this
Charge – cont’dGroups 1 = +1, 2 = +2, 13 = +3
want to lose electrons
Charge – cont’dGroup 14 = +/- 4 will gain or lose
electrons equallygain/loss depends on what it bonds to
Charge – cont’dGroups 15 = -3, 16 = -2, 17 = -1, 18 = 0
want to gain electrons
Charge – cont’dgroup 18 will not gain, lose, or share e-s
[bc they have 8 e-s anyway]
Charge – cont’dWhich is the more “positive term:
Charge – cont’dUseful chemistry terms:cation – positively charged atom
mostly metalsanion – negatively charged atom
mostly non-metals
Oxidation #Oxidation Number – the number of e-s an
atom will gain, lose, or share in order to become stablebasically the same as the charge on the PTagain, leave out groups 3-12GROUP number indicates
the number of outer-shell e-sgroups 1, 2, then groups 13-18 (except
He)Always 4 or less [+ or -]
Oxidation/Charge Numbers +1 +2 ----------------------------------------- +3 +/-4 -3 -2 -1 0
In order to become stable……an Oxygen atom an will…
lose 6 e-s gain 6 e-s lose 2 e-s gain 2 e-sOR none of the above
…a Calcium atom will… lose 6 e-s gain 6 e-s lose 2 e-s gain 2 e-s
OR none of the above
… a Sodium atom will…lose 7 e-s gain 7 e-s lose 1 e-s, gain 1 e-
OR none of the above
In order to become stable……a Bromine atom an will…
lose 7 e-s gain 7 e-s lose 1 e-s gain 1 e-s OR none of the above
…a Xenon atom will… lose 8 e-s gain 8 e-s lose 0 e-s gain 0 e-s
OR none of the above
The Periodic TablePeriodic = in a regular, repeating fashion
Early designs of the PT were based on use, physical properties, and even spelling.
Mendeleev’s ContributionsOrganized first working Periodic Table
according to chemical properties and atomic mass
Left gaps for undiscovered elementsHe was able to predict many properties of
these undiscovered elements based on their location
Periodic Table – cont’dcolumn = group/family
elements in a family have the same chemical properties [valence e-s, reactivity…]row =
periodproperties
of elements repeat across a period [size of atom, ease of losing e-s]
Group 1 Alkali MetalsHighly reactive metals2ectron
Group 2Alkaline Earth MetalsReactive metalsHave two outer shell electrons
Groups 3-12Transition Metals“normal” metalshave one to ten outer shell electrons
Groups 3-12 cont’dLanthanide (57-71) & Actinide (89-103) series
can be considered to be “inner” transition metals.
Metals vs. Non-MetalsMetals Non-Metals
Location left of the “stairs”
right of the “stairs
Appearance lustrous waxy or dull
“Shape-ability” malleable & ductile
brittle
Conductivity[heat & electricity]
very good poor - better as insulators
Physical State solid at room temp [except Hg]
gas or solid at room temperature [except Br]
Charge typically cations typically anions
MetalloidsMay have properties of metals and nonmetalsLocated on the stair-stepSome are semiconductors:
they only conduct electricity under certain conditionsThis makes metalloids
excellent switches for computers
Group 17Halogens
Means “Salt Former”Highly reactive nonmetalsHave seven outer shell electrons
Group 18Noble GasesCompletely unreactive nonmetals
Will not bond with any atomHave a full outer shell of electrons
Eight for all but HeliumHe has two outer shell electrons
PracticeWhich group is known as the Halogens?
Group 1, Group 2, Groups 3 – 12, Group 17, Group 18
Which group has a stable number of outer shell electrons?Group 1, Group 2, Groups 3 – 12,
Group 17, Group 18What is the group name for Group 2?
Alkaline Earth Metals, Alkali Metals, Halogens, Transition Metals, Noble Gases
Practice Which group is known as the Transition
Metals?Group 1, Group 2, Groups 3 – 12,
Group 17, Group 18Which group has two outer shell electrons?
Group 1, Group 2, Groups 3 – 12,Group 17, Group 18
What is the group name for Group 18?Alkaline Earth Metals, Alkali Metals,
Halogens, Transition Metals, Noble Gases
Practice Elements of which group are known as the
Alkali Metals?Group 1, Group 2, Groups 3 – 12,
Group 17, Group 18Elements of which group have a variable
number of outer shell electrons?Group 1, Group 2, Groups 3 – 12,
Group 17, Group 18
Practice Which scientist arranged elements in a
working Periodic Table?Galileo, Aristotle, Al-Gebbri, Mendeleev
Which property of elements is the basis for arrangement in the Periodic Table?Atomic Mass, Boiling Point,
Number of Neutrons, Chemical Properties
Which subatomic particle determines the chemical properties of an element?Protons, Neutrons, Electrons, Quarks
PracticeVertical columns on the Periodic Table are
Groups, Rows, Periods, Clans
How many valence electrons would Sulfur have? (Group 16)2, 6, 8, 16, 32
Nonmetals are locatedTo the left of the stair-step, On the stair-step,
To the right of the stair-step, At the very bottom
ProblemsWhich group on the Periodic Table are known
as “Halogens”?Group 1, Group 2, Groups 3 – 12,
Group 17, Group 18
Ductile, Malleable, & solid at room temp.Metalloids, Nonmetals, Metals, Yoda
Usually gas at room temp., brittle, dull or waxyMetalloids, Metals, Nonmetals, Your HAIR!
Electronegativityability to hold onto outer valence e-s
high electronegativity = tightly held e-slow electronegativity = loosely held e-s
Electronegativity – cont’dincreases as you go from left to right across a
period. easier to give away a few [like those to the
L] than to steal many [like those on the R]
Electronegativity – cont’ddecreases as you go down a group.
“every electron matters” – those with many can afford to lose some, those with little can’t
electrons shield the nucleons [protons & neutrons]
the farther out electrons are from the nucleus, the less tightly held they are [away from + charge]
Reactivityhow likely or vigorously an element reacts
with othersMetals:
decreases as you go from left to right across a period.
reactivity increases as you go down a group .
Why? It’s easier for those elements to get rid of electrons.
Reactivity – cont’dNon-Metals:
increases as you go from the left to the right across a period.
decreases as you go down the group. Why? It’s easier for those elements to steal
electrons.
Atomic Radiusdecreases as you go from left to right across
a period. attractive forces btw opposite charges
(electrons outside / protons inside) cause cloud to be 'sucked' together a little tighter.
Atomic Radius – cont’dincreases as you go down a group.
Why? Large jump in size of nucleus (p+s + n0s) each time you move from period to period down a group.
also, new E levels added when moving down periods
Alkali metals (not H) (1)Alkaline earth metals (1)
Transition metals (1)Halogens (1)Noble gasses (1)Inner transition (1)
Gs and Ls correct (1)
Legend filled in (1)
G GGG
GG
G GGG
GG
L
L
VIIAVIAVAIVAIIIAIIAVIIAIA
Marks: 10Total: 20
Metalloids (1)IA, IIA, etc. labels (1)